JP2001205431A - Underwater pulsed arc welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an underwater high-frequency pulse welding device which has excellent controllability of a torch driving part for adjusting arc length. SOLUTION: The underwater pulsed arc welding device is provided with a welding torch having an arc electrode, a pulse welding power source which supplies high-frequency pulse current to the arc electrode, the torch driving part which has a servomotor or the like and adjusts a space between the arc electrode of the welding torch and a welding parent metal and an arc voltage detecting part which detects voltage between the arc electrode and the welding parent metal. The underwater pulsed arc welding device is distinguished by that an average value of the arc voltage during a time range from a rising start up point till rising finish point of the pulsed arc voltage is obtained by an averaging treating part and the torch driving part is adjusted-operated so that the obtained average voltage value coincides with an arc voltage reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel underwater high-frequency pulse arc welding apparatus, and more particularly to an underwater high-frequency pulse arc welding apparatus suitable for TIG welding using non-consumable electrodes. This welding apparatus is applicable to underwater welding of nuclear reactors, ships, and the like.

[0002]

2. Description of the Related Art In direct current arc welding, since the arc voltage and the arc length have a certain relation, the arc electrode of a torch is moved so that the detected arc voltage is maintained at a predetermined value. In order to adjust (the distance between the arc electrode and the welding member), a servo motor or the like of the distance adjusting means is controlled. In pulse arc welding, a pulse current and a base current are supplied to an arc electrode together, and a time-varying pulse arc voltage is also averaged together. Had control.

As a pulse arc welding method, there is a method using a frequency region of a low frequency region (1 to 20 Hz), an intermediate wave region (20 to 1000 Hz), and a high frequency region (1 to 25 kHz). In the low frequency region and the intermediate frequency region, the OF in which the pulse current becomes zero in one cycle
When the F section is provided, a relatively large base current has to flow in order to suppress the disappearance of the arc and the deterioration of stability.

Since the cycle is short in the high frequency region, as shown in FIG. 12, the arc can be sustained with a relatively small base current.

[0005] In high-frequency pulse arc welding, a high peak value pulse current can be obtained by setting a small base current without significantly increasing the total welding current. By flowing the current having the high peak value, the electromagnetic pinch force is strengthened, the directivity of the arc is enhanced, and accurate welding can be performed without deviation. Therefore, the present invention is suitable for welding a narrow groove (narrow groove).

[0006] As a high-frequency pulse arc welding apparatus, there is an apparatus provided with a plurality of IGBTs as shown in Japanese Patent Application Laid-Open No. H11-28568.

The arc length of such a high-frequency pulse arc welding apparatus is controlled on the basis of the average value of the pulse arc voltage obtained by one-cycle averaging because the pulse arc voltage changes with time. ing.

[0008]

The above-described conventional arc length control of the high-frequency pulse welding apparatus has the following problems.

(1): The arc length control of a high-frequency pulse welding apparatus for welding with a pulse current having a high current peak value at a frequency of 1 to 25 kHz and a base current having a small current value is performed by a pulse cycle (ON section and OFF section). (The total time of the section) based on the average value of the pulse arc voltage.

However, the average value of the pulse arc voltage is O
Since it is the average value of one cycle of the pulse including the FF section, the value is small. Looking at the relationship between the average value of the pulse arc voltage indicating this small value and the arc length, the ratio of the change amount of the pulse arc voltage average value to the change amount of the arc length (arc voltage sensitivity) is small. The control of the torch drive unit for adjusting the arc length with the average value of the pulse arc voltage having a low arc voltage sensitivity has low response and poor controllability.

(2): When using a high-frequency high current having a pulse current frequency of 1 to 25 kHz or more,
High frequency induction noise [inductance (L) × (current change time)] is generated, and this high frequency induction noise is superimposed on the pulse arc voltage. As a result, the relationship between the arc voltage and the arc length changes, and particularly in a region where the arc length is small, the arc voltage sensitivity is further reduced, and the control of the torch drive unit becomes even less responsive. An object of the present invention is to provide an underwater high-frequency pulse welding apparatus that enhances shielding performance under a special environment of underwater and has good controllability of a torch drive unit for adjusting an arc length.

[0012]

SUMMARY OF THE INVENTION The present invention relates to a welding torch having an arc electrode, a pulse welding power supply for supplying a high-frequency pulse current for periodically generating a high-frequency pulse arc voltage to the arc electrode, a servomotor, and the like. And a torch drive unit for adjusting the distance between the arc electrode of the welding torch and the welding base material, and an underwater pulse including an arc voltage detecting unit for detecting a voltage between the arc electrode and the welding base material In the arc welding apparatus, there is provided an ON-time averaging processing section for obtaining an average value of the arc voltage in a time section from a rising start point to a falling end point of the pulse arc voltage, and the ON-time averaging processing section obtained by the ON-time averaging processing section is provided. The torch driving unit is operated so as to adjust so that the section average voltage value and the arc voltage reference value substantially coincide with each other.

Further, the present invention, in addition to the means having the above characteristics, performs the waveform shaping process of the arc voltage by a low-pass filter circuit, and obtains an ON section average value after performing the waveform shaping process. It is a feature.

Further, the present invention is provided with a shield means for locally shielding a welded portion with a non-oxidizing gas when welding is performed by a heat source by an arc in water, wherein the shield means is located near the heat source. And a flexible structure that can expand and contract according to the shape of the workpiece.

According to the shield means according to the present invention, since the shield means is constituted by a woven fabric of heat-resistant fiber, the work piece can be easily expanded and contracted following the Heisei shape of the work piece. Is uniformly formed, so that the flow of the shielding gas becomes uniform over the entire circumference, and high quality and good welding or the like can be obtained.
Furthermore, since the gaps are uniform, the amount of shielding gas used can be reduced. In addition, since these effects can be formed close to a heat source because heat-resistant fibers are used as the shielding means, the structure can be made more compact and further enhanced.

[0016]

(Embodiment 1) FIG. 1 is a configuration diagram of a high-frequency pulse welding apparatus according to the present invention. Pulse welding power supply 1
And a welding torch 3 having an arc electrode 2 and a torch drive unit 4. The arc electrode 2 is placed so as to face a welding position of the base material 5. Torch drive 4 (servo motor)
Moves the welding torch 3 back and forth so as to adjust the arc length of the arc 6 generated between the arc electrode 2 and the base material 5. The welding torch 3 discharges a shielding gas so as to surround the arc 6 and suppresses oxidation of a welded portion.

The pulse welding power source 1 and the welding torch 3 are connected by a pulse current transmission cable 19, and a pulse current detection unit 21 is provided between them. The pulse welding power supply 1 generates a constant current pulse based on the pulse current detection value 26 detected by the pulse current detector 21.

The pulse welding power supply 1 and the base material 5 are connected by a pulse current transmission cable 20, and an arc voltage detector 8 is provided between the pulse current transmission cable 20 and the welding torch 3. The arc voltage detection value 25 detected by the arc voltage detector 8 is taken into the ON averaging processor 9 and processed. The average value of the ON section of the arc voltage obtained in this process is taken into the half-wave rectifier circuit 10 and compared with the arc voltage reference value. The output of the half-wave rectifier circuit 10 drives the torch drive unit 4. When the average value of the arc voltage matches the arc voltage reference value and the output of the arc voltage comparison unit 10 becomes zero, the adjustment driving operation of the torch drive unit 4 stops.

The pulse welding power source 1 has a plurality of IGBTs and supplies a pulse current having a pulse frequency of 1 to 25 kHz. By reducing the inductance of the power supply circuit and the pulse current transmission cable 19, 10 to 10
The current rises from 0 to 500 amps in a short time of 50 μsec, and the current rises to 500 to 0 in a similar short time.
A pulse current falling to ampere is obtained. The waveform of this pulse current has a high peak value, and FIG.
As shown in (b), a triangular shape or a trapezoidal shape whose upper side is inclined is shown. The base current is zero or one of the peak values.
By giving a current value of / 10 or less, the arc current flows continuously without interruption. This base current value was reduced to about 1/5 of the conventional base current value.
In addition, the peak value of the pulse current is appropriately about 300 to 800 amperes in view of the directivity of the arc, the total welding current, and the like.

The ON-time averaging processing section 9 calculates an ON-section average voltage value of the arc voltage in a time section from a rising start point to a falling end point when the arc voltage absolute value of a predetermined polarity is equal to or more than a predetermined value. is there. As shown in FIG. 2, the ON-time averaging processing unit 9 includes a pulse width measurement circuit 11, an arc voltage integration circuit 12, and an arithmetic processing circuit 13.

The pulse width measuring circuit 11 sets an arc voltage reference value using a comparator, and as shown in FIG. 8, changes from the rising start point at which the arc voltage absolute value of a predetermined polarity becomes equal to or more than the predetermined value Vb to the falling end point. Time section (t1
To t2), the pulse width Tp (Tp = t2−t1).

The arc voltage integration circuit 12 integrates the arc voltage when the pulse is ON, and holds the voltage during the OFF section.
The arithmetic processing circuit 13 divides the integrated value by the pulse width Tp to obtain 1
The average value of the arc voltage in the pulse ON section is obtained for each pulse. Further, an average value for a plurality of pulses is obtained.

When the pulse width measuring circuit for the current pulse is incorporated in the welding power source 1, the pulse width measuring circuit 11 of the ON-time averaging unit 9 becomes unnecessary.

As described above, the average value of the arc voltage in the time section in which the absolute value of the arc voltage is equal to or more than the predetermined value Vb is obtained by the on-time averaging processing section 9, and the average value of the arc section in the ON section is set to the arc voltage reference value. Since the drive control of the torch drive unit 4 is performed using the difference value, the control of the arc length is improved.

That is, as shown in FIG. 9, the relationship between the average value of the ON section of the arc voltage subjected to the ON-time averaging process and the arc length is indicated by oblique line A. On the other hand, the relationship between the average value of the arc voltage and the arc length when the conventional one-cycle averaging process is performed is shown by oblique lines B. The slopes of these oblique lines A and B indicate the arc voltage sensitivity, which is the ratio of the change amount of the average value of the pulse arc voltage to the change amount of the arc length, and the oblique line A according to the present invention is more inclined than the conventional oblique line B. Is large, and the change in the average value of the pulse arc voltage is large for the same change in the arc length, which indicates that the sensitivity is high.

The control of the torch drive unit for adjusting the arc length based on the average value of the pulse arc voltage having good voltage sensitivity has good response and good control can be performed.

Further, when the welding current is reduced while keeping the peak current constant, as shown in FIG. 10, the average value of the arc voltage subjected to the conventional one-cycle averaging process is reduced. This is because the pulse duty (the ratio of the pulse ON time to the pulse period) decreases as the welding current decreases.

On the other hand, the pulse ON according to the present invention is turned on.
The average value of the arc voltage in the section is substantially constant because it is not affected by the change in the welding current. For this reason, even when welding is performed under a low heat input condition by reducing the welding current, the average value of the arc voltage can be prevented from being reduced and the arc voltage sensitivity can be prevented from lowering, so that the control of the torch drive unit can be performed well. Another circuit configuration example of the ON-time averaging processing unit shown in FIG. 3 will be described.

The ON-time averaging processor 9 shown here has a half-wave rectifier circuit 10 in addition to the ON-time averaging processor 9 shown in FIG. Things.

The half-wave rectifier circuit 10 obtains a one-cycle average value Va by passing only a predetermined polarity of the pulsed arc voltage and averaging the arc voltages. The pulse width measurement circuit 11 determines the pulse width Tp, and the pulse cycle measurement circuit 14 determines the pulse cycle T. Then, in the arithmetic processing circuit 15, Va ×
The arithmetic processing of (T / Tp) is performed, and the arithmetic processing of calculating the average value Vn [Vn = Va × (T / Tp)] of the arc voltage when the pulse is ON is performed. Since the torch drive unit 4 is drive-controlled based on the average value Vn of the arc voltage at the time of the pulse ON thus obtained, the arc voltage sensitivity to the arc length can be increased, and as a result, the arc length can be controlled well.
Even in this circuit configuration example, good control similar to that of the first embodiment described above can be performed.

It is desirable that the half-wave rectifier circuit 10 be configured so that the bias voltage can be set equal to the base voltage Vb generated in the base current section. As a result, a one-cycle average value Va from which the base voltage has been removed is obtained.
A more accurate average value of the arc voltage when the pulse is ON can be calculated. Further, the pulse width measurement circuit 11 and the pulse period measurement circuit 14 may be for the current pulse, and when they are incorporated in the welding power source 1, the ON-time averaging processing unit 9 does not need to be provided.

(Embodiment 2) FIG. 4 is a configuration diagram of a high-frequency pulse welding apparatus according to the present invention.

The ON-time averaging unit 9 shown in FIG.
As shown in the figure, the timing circuit 27, the multiplication circuit 16, the integration circuit 17, the pulse width measurement circuit 11, and the arithmetic processing circuit 15
Is provided.

The timing circuit 27 forms a square wave in the time section in which the current pulse is turned on as shown in FIG. 13 while taking the pulse current detection value 26 into consideration.

The multiplication circuit 16 multiplies the square wave by the arc voltage waveform to extract an arc voltage in a time section in which the current is turned on. The integrating circuit 17 integrates the arc voltage when the pulse is ON, and holds the value during the pulse OFF section. The integral value is divided by the pulse width in the arithmetic processing circuit 15 to obtain an average arc voltage in the current ON section.

Since the torch drive unit 4 is driven and controlled based on the average value of the arc voltage during the time period when the current is turned on, the arc voltage sensitivity to the arc length can be increased, and as a result, the control of the arc length can be improved. It can be carried out.

Also in this embodiment, as in the first embodiment, good control can be performed even when welding is performed under a low heat input condition with a small welding current.

In this embodiment, when the pulse electrode has a single polarity, a half-wave rectifier circuit may be used for the integrating circuit 17, but when a full-wave rectifying circuit is used for the integrating circuit 17, the pulse electrode can be used. There are advantages that can be applied to both unipolar or bipolar. That is, in the ON-time averaging processing unit 9, the full-wave rectifier circuit is used for the integration circuit 17 and the pulse welding power source 1 capable of generating both unipolar and bipolar current pulses is provided, so that the welding base material is reduced. It is convenient to select a single polarity when stainless steel or carbon steel is used, and to select bipolar when the welding base material is aluminum.

(Embodiment 3) FIG. 6 is a configuration diagram of a high-frequency pulse welding apparatus according to the present invention.

The difference from the first embodiment lies in that a voltage waveform shaping circuit 18 is interposed between the arc voltage detecting section 8 and the ON-time averaging processing section 9. The high frequency induction noise entering the ON-time averaging processing unit 9 is removed by the voltage waveform shaping circuit 18. Specific examples of the voltage waveform shaping circuit 18 include a low-pass filter circuit whose threshold value is equal to or slightly higher than the current pulse frequency, and an isolation amplifier circuit having a characteristic of cutting high-frequency components.

When a high-frequency high current of 1 to 25 kHz or more is generated by the pulse welding power supply 1, high-frequency induction noise [inductance (L) × (time change of current)] tends to occur. When this high frequency induction noise is superimposed on the arc detection voltage of the arc voltage detection unit 8 via the pulse current transmission cables 19 and 20, the relationship between the arc voltage and the arc length changes as shown by a dotted line A in FIG. In particular, it was found that the arc voltage sensitivity was reduced in the region where the arc length was small. Due to the decrease in the arc voltage sensitivity, the adjustment of the arc length based on the average value of the ON section of the arc voltage obtained by the ON-time averaging processing unit 9 deteriorates the drive control of the torch drive unit 4, and is not performed well.

On the other hand, by interposing the voltage waveform shaping circuit 18 and cutting the high-frequency component of the current pulse of 1 to 25 kHz with a low-pass filter circuit having a threshold of 30 to 50 kHz, FIG.
As shown by the solid line C, it was found that the arc voltage sensitivity did not decrease even in the region where the arc length was small.

Therefore, in the present invention, the high-frequency induction noise is removed by the voltage waveform shaping circuit 18 before the high-frequency induction noise is taken into the on-time averaging processing section 9, so that the torch drive section 4 is removed.
The drive control accuracy is improved, and the arc length is adjusted well. Particularly, in an area where the arc length is short, there is an effect that the arc voltage sensitivity is reduced and the controllability is prevented from being deteriorated.

The arc voltage waveform when the above-mentioned noise is removed is almost the same as the current waveform as shown by the broken line in FIG.

(Embodiment 4) FIG. 14 is a sectional view of a high-frequency pulse welding apparatus according to the present invention.

In the first to fifth embodiments, the averaging processor 9 in the ON state is replaced by an arc power calculator 22, the arc voltage comparator 10 is replaced by an arc power comparator 23, and an arc power display 24 is provided. Different from 3.

The arc power calculator 22 includes a multiplication circuit 16, an integration circuit 17, an arithmetic processing circuit 15,
A pulse width measuring circuit 11 and a pulse period measuring circuit 14 are provided. The signals from the pulse current detecting section 21 and the arc voltage detecting section 8 are multiplied by an instantaneous voltage × instant current (V ×
The calculation of I) is performed, the integration is performed by the integration circuit 17, and the calculation circuit 1
At 5, the integrated value is divided by the cycle T to determine the average value Wa of the arc power per cycle. The arithmetic circuit 15 calculates Wa × (T / Tp) to calculate an average value Wn [Wn = Wa × (T / Tp)] of the arc power when the pulse is ON. Further, an average value for a plurality of cycles and a plurality of pulses is calculated for Wa and Wn.

When the relationship between the arc length and the average value of the arc power was examined, as shown in FIG. 16, there was a relationship similar to the relationship between the arc length and the average value of the arc voltage described above (FIG. 9). I understood that. That is, pulse ON
It was found that by using the average value of the arc power at the time, the arc power sensitivity with respect to the arc length was larger than the case where the one-cycle average arc power was used. Even when the welding current is small, the average value of the arc power at the time of the pulse ON does not significantly decrease.

Therefore, since the drive control of the torch drive unit 4 is performed based on the average value Wn of the arc power at the time of the pulse ON, the sensitivity of the arc power to the arc length can be increased. As a result, the control of the arc length can be improved. Done. When welding is performed under a low heat input condition with a small welding current, there is an effect that the arc power consumption can be made substantially constant in addition to the good control of the arc length. Further, by providing the pulse welding power source 1 capable of generating a unipolar or bipolar current pulse, a unipolar is selected when the welding base metal is stainless steel or carbon steel, and a bipolar polarity is selected when the welding base metal is aluminum. There is convenience to choose.

Further, if the detected one-cycle average power Wa is displayed or printed on the arc display unit 24, the user can easily grasp the heat input condition at the time of welding and set the welding condition easily.

In particular, in high frequency pulse welding, since the pulse waveform has a triangular waveform or a trapezoidal shape whose upper side is inclined, power consumption cannot be immediately calculated from the average value of welding current and arc voltage. The effect that can be done is great.

[0052]

(Equation 1)

[0053]

(Equation 2)

Although the average value of the arc voltage is obtained and used as Vn by the equation (1) in the above-mentioned ON-time averaging processing section 9, the root-mean-square of the ON section is expressed by (2)
Vnrms in the equation may be obtained and used. (1)
In the equations (2), v (t) represents the instantaneous arc voltage.

In the current control, the peak current (for example, 500
A) is made substantially constant, and a predetermined pulse width (30 to 100 μm) is set.
s), a method of changing the frequency (FM control) may be used, or a predetermined frequency (5 to 15 kHz) may be used.
Method of changing pulse width for z) (PWM control)
May be used. The arc power calculator 22 of the present example is for calculating the average value of the arc power.

According to the present invention, in a pulse arc welding apparatus having a pulse welding power source 1 and a welding torch 3, the above-described arc power calculation unit 22 is provided to detect arc power (an average value per cycle) and to detect the arc power. A control signal is sent to the torch drive unit 4 so that the detected value becomes equal to the reference value, and the arc length is changed to control the arc power.
FIG. 16 is a diagram showing the relationship between the arc length and the arc power. FIG. 16 shows that, under a predetermined pulse current, increasing the arc length increases the arc power, and decreasing the arc length decreases the arc power.

In such a configuration, when the frequency or the pulse width changes and the arc power changes due to the fluctuation of the peak current during welding, a control signal is sent to the torch drive unit 4 to raise or lower the torch, thereby reducing the arc power. Set the arc length to be the reference value. Therefore, since the arc power at the time of welding can be kept constant, there is an effect that variations in welding quality can be prevented.

Further, an arc power display unit 24 is provided to display the detected arc power, or a calculation unit for obtaining the heat input from the detected arc power and the welding speed (moving speed of the torch holding carriage) and a heat input display unit. If the heat input amount is provided and the heat input amount is displayed, the welding user can easily grasp the heat input condition at the time of welding, and there is an effect that the setting of the welding condition becomes easy.

If the arc power value input by the user as a setting condition cannot be realized within the range of the already input current value and a predetermined arc length (for example, 0.7 to 2.0 mm),
(1) An error display may be performed, and the user may re-input the current value or the arc power value. (2) The relation data (for example, FIG. 3) between the current and the arc length and the arc power obtained in advance may be displayed. CP arranged in the control unit of the pulse welding power supply 1
U, and based on this relational data, the predetermined arc length
The current value at which the set arc power can be realized for an intermediate arc length of 1.5 mm may be automatically determined and set.

(Embodiment 5) FIG. 17 shows an underwater TIG welding apparatus of the present invention using the high-frequency pulse welding apparatus described in Embodiments 1-4. When welding a base material 5 which is a material to be welded in an underwater environment, the pulse welding power supply 1 is installed in the atmosphere, and only a portion of the welding torch 3 where an arc 6 is generated is installed in water. Here, the shielding gas 36 is used to locally exclude water (the welding portion is shielded) so that the welding torch and the welding portion 35 do not come into contact with water. As a method for removing water, gas, water, solid walls, and the like are effective. In this embodiment, a highly elastic solid wall made of a felt-like cloth woven from carbon fiber having a thickness of about 5 mm is used as a shielding means. 3
7 and an Ar gas were used in combination.

In this embodiment, since the solid wall 37 is made of heat-resistant felt-like carbon fiber and steel wool woven fabric for the lower skirt portion, the solid wall 37 can be made close to the torch portion, so that it can be made compact. And
As shown in the figure, it spreads out like a trumpet, but it has a certain degree of elasticity in the radial and vertical directions so that it can be in close contact with the welded part, so that it can move following the irregularities in the welded part, Inflow is suppressed, and defect-free welding becomes possible. In automatic arc welding, it is necessary to perform welding with a constant arc length, but for this the welding torch is automatically adjusted because it fluctuates slightly up and down,
Accordingly, the solid wall 37 must have elasticity. This elasticity is essential in automatic welding.

FIG. 18 is a sectional view of a device for optically monitoring the inside of a local shield of the underwater TIG welding device. The optical surveillance camera 38 is installed in the camera holder 30 provided with heat-resistant glass 39 on the entire surface, and observes the inside of the local shield. The camera holder 30 is attached to a monitoring nozzle 31. The monitoring nozzle 31 is installed on the welding torch 3 and moves similarly to the welding torch. Monitoring nozzle 3
A felt-like solid wall 37 made of carbon fiber is attached to the skirt of the first member as a shielding means, and the solid wall makes good contact with the base material 5 to prevent water from entering. The shielding gas 36 using Ar passes through the welding torch 3 and the gas nozzle 3
2 and is ejected into the inside of the local shield 33 and discharged into the water through the solid wall of the carbon fiber. This device can monitor the processing state well without being affected by gas bubbles released into water. (Embodiment 6) FIG. 19 is a perspective view of an underwater TIG automatic welding apparatus which is fully systemized using the underwater TIG welding apparatus shown in Embodiment 5.

By inputting arbitrary welding conditions to the welding control device 46, electricity is sent from the welding power source 47 to the welding torch 3, and an arbitrary shielding gas is sent from the gas cylinder 48 to perform welding. In this embodiment, a method in which a monitoring camera is installed inside the local shield mechanism will be described. A surveillance camera 38 is installed on the solid wall 37 using carbon fiber to monitor the processing state. A large amount of Ar gas bubbles 49 used as shielding gas are generated from the bottom of the solid wall. This welding torch 3
Before and after, the underwater monitoring device 42a for confirming the groove shape 50 and the welding position and the underwater monitoring device 42b for monitoring the quality of the welded portion 51
Place. Here, a solid wall 57 using carbon fiber is provided to obtain a stable cavity. In addition, a small CCD camera of a solid-state picture tube system was used as a monitoring camera.

First, the groove shape and welding position are confirmed by the underwater monitoring device 42a. The video captured by the surveillance camera is sent to the image processing device 52a as an electric signal.
Here, the deviation from the initial shape and position is calculated and determined. If the groove shape is deviated from the prescribed amount, a signal for changing the welding condition is sent to the welding control device 46, and the setting is changed to the welding condition for performing appropriate welding. If the welding position is displaced from the specified amount, a signal for correcting the displaced amount is sent to the welding carriage 53 so that welding is performed at an appropriate position. In this case, the welding torch 4 and the underwater monitoring device 42a
Is confirmed, and a delay time is set in advance.

FIG. 20 is a more specific perspective view of the underwater automatic welding apparatus.

The underwater welding system is roughly divided into a control device on the water and a welding device in the water. The method of feeding the welding wire is as follows. In the case where the feed is controlled by a push-pull feeding method, and it is difficult to control the feed of the push-pull wire deeply, there is a method of mounting a welding wire on an underwater welding apparatus. An image processing device 100, a push-side welding wire feeding device 91, control power supplies 46 and 47 for welding and welding devices, and a welding shield gas cylinder 48 are installed in the control device on the water.

Hose and welding cables 97, such as a conduit tube 94 for supplying a welding wire, a hose 95 for supplying a shielding gas, a hose 96 for supplying a water jet, and the like, are provided between the control device on the water and the welding device in the water. They are connected by cables such as a cable 98. In the underwater welding device, a traveling carriage rail 110 is laid in parallel with the welding line 99 of the workpiece 82, and a traveling carriage 101 having a welding traveling drive device travels thereon, and the traveling carriage 101 Underwater welding torch (hereinafter referred to as underwater welding torch) 102 manufactured based on the above-mentioned underwater welding method for workpiece 82
A position adjustment driving device 103 for adjusting the position of the
Pull side welding wire feeding device 104 and underwater welding torch 1
02 is provided. In this underwater welding equipment,
It has the advantage that it can be welded continuously for a long time.

The solid wall 37 is made of felt made of carbon fiber having a desired thickness at the tip of the torch as in the above-described embodiment.

(Embodiment 7) FIG. 21 shows an underwater TI of Embodiment 6.
Shroud of nuclear power plant using G automatic welding equipment 8
2 is shown, and FIG. 21 is an enlarged view of FIG. A large amount of radiation is emitted from the internal structure of a nuclear power plant. In particular, in repair welding of structures such as the shroud 82, the upper grid plate 83, and the steam dryer 84 in the pressure vessel 81 in which the fuel rod 80 is stored, underwater welding that can be automatically and remotely controlled in consideration of worker safety. It is thought to do. The solid wall 37 is made of carbon fiber.

At the time of periodic inspection of the nuclear reactor, a portion requiring repair such as a defect is detected. For this, an ultrasonic diagnostic method, a light section method, a direct observation method, or the like is used. When the occurrence of a defect is confirmed, repair work is performed, but the repair method differs depending on the shape of the repaired portion, the degree of the defect, and the like. If the defect is large,
After the defects are completely removed by electric discharge machining or the like, overlay welding is performed. In addition, there is a method in which build-up welding is performed as it is for small defects, and a method of performing heat treatment on the surface where defects are expected. After completion of repair welding, its quality must be monitored. For this, a method of indirectly observing the welded portion, a method of diagnosing with a ultrasonic wave, and the like are preferable. These underwater working devices are installed in a moving mechanism having X, Y, and Z directions and a rotation axis, and the above devices can be remotely installed at any position.

The underwater welding apparatus includes a welding power source 85 installed in the atmosphere (outside the pressure vessel or a place where there is no influence of water).
More electric power is supplied, arbitrary welding conditions are given by the controller 86, and the torch 8 installed underwater through the cable 87.
An arc is emitted from 8 and welding is performed. The processing state is monitored by a monitoring camera 90 installed on a monitoring nozzle 89. In the above-mentioned underwater repair welding work, the applicable range of the underwater processing apparatus of the present invention is wide. First, the direct observation method in the defect search operation is performed using an underwater monitoring device. It is necessary to monitor the electric discharge machining in the work of removing defects, and the present monitoring device can be applied to the machining state and quality control after the machining.

Other repair parts in this embodiment include a steam separator 84, a core support plate 80, an upper grid plate 83, a control rod housing, and a control rod drive mechanism housing.

[0073]

As described above, according to the present invention, underwater welding can be provided by using a high-frequency pulse welding apparatus having good controllability of the torch drive unit for adjusting the arc length.

[Brief description of the drawings]

FIG. 1 is a schematic view of a high-frequency pulse welding apparatus according to the present invention.

FIG. 2 is a block diagram of an ON-time averaging processing unit shown in FIG. 1;

FIG. 3 is a block diagram illustrating another example of the circuit configuration of the ON-time averaging processing unit;

FIG. 4 is a schematic view of a high-frequency pulse welding apparatus according to the present invention.

FIG. 5 is a block diagram of an ON-time averaging processing unit shown in FIG. 4;

FIG. 6 is a schematic view of a high-frequency pulse welding apparatus according to the present invention.

FIG. 7 is a diagram showing waveforms of a pulse current and a pulse voltage.

FIG. 8 is a diagram showing a waveform of an arc voltage.

FIG. 9 is a diagram illustrating a relationship between an arc length and an average value of an arc voltage.

FIG. 10 is a diagram showing a relationship between a welding current and an average value of an arc voltage.

FIG. 11 is a diagram showing a relationship between an arc length and an average value of an arc voltage.

FIG. 12 is a diagram showing a peak value and a base value of a current pulse.

13 is a diagram illustrating a square wave formed by the timing circuit of the averaging processing unit during ON shown in FIG. 4;

FIG. 14 is a schematic view of a high-frequency pulse welding apparatus according to the present invention.

FIG. 15 is a block diagram of an arc power calculator shown in FIG. 14;

FIG. 16 is a diagram showing a relationship between an arc length and an average value of arc power.

FIG. 17 is an overall configuration diagram of an underwater TIG welding apparatus exemplified in the embodiment of the present invention.

FIG. 18 is a cross-sectional view when the engineering monitoring device is installed inside the local shield.

FIG. 19 is an overall view illustrating a system of the underwater welding monitoring apparatus according to the present invention.

FIG. 20 is a perspective view of an underwater welding device according to the present invention.

FIG. 21 is a configuration diagram in which the present invention is applied to welding in a nuclear reactor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Pulse welding power supply, 2 ... Arc electrode, 3 ... Welding torch, 4 ... Torch drive part, 5 ... Base material, 6 ... Arc, 7 ... Shield gas, 8 ... Arc voltage detection part, 9 ... ON averaging process Part, 10: half-wave rectifier circuit, 11: pulse width measurement circuit, 12: arc voltage integration circuit, 13: arithmetic processing circuit,
14: pulse cycle measuring circuit, 15: arithmetic processing circuit, 16
... multiplier circuit, 17 ... integrator circuit, 18 ... voltage waveform shaping circuit, 19, 20 ... pulse current transmission cable, 21 ... pulse current detector, 22 ... arc power calculator, 23 ... arc power comparator, 24 ... arc power Display unit, 25: detected arc voltage, 26: detected pulse current, 27: timing circuit, 31: monitoring nozzle, 33: inside local shield, 3
5 ... welded part, 36 ... shielding gas, 37 ... solid wall, 38
... optical monitoring camera, 41 ... cylindrical tube, 42 ... underwater monitoring device main body, 42a ... underwater monitoring device for checking groove shape and welding position, 42b ... underwater monitoring device for monitoring quality of welded part,
50 ... groove shape.

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[Procedure amendment]

[Submission Date] February 18, 2000 (2000.2.1
8)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction contents]

[0048] Also was examined the relationship between the average value of the arc length and arc power was found to have similar relationship with the relationship between the average of the previous mentioned arc length and arc voltage (Fig. 9). That is, it was found that the use of the average value of the arc power at the time of the pulse ON makes the arc power sensitivity to the arc length larger than the case where the one-cycle average arc power is used. Even when the welding current is small, the average value of the arc power at the time of the pulse ON does not significantly decrease.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction contents]

[0056] The present invention, in the pulse arc welding apparatus having a pulse welding power source 1 and the welding torch 3, the arc power calculator 22 described above is provided to detect the arc power, the detected value of the arc power is equal to the reference value The control signal is sent to the torch drive unit 4 to change the arc length so as to control the arc power. FIG. 16 is a diagram showing the relationship between the arc length and the arc power. FIG. 16 shows that, under a predetermined pulse current, increasing the arc length increases the arc power, and decreasing the arc length decreases the arc power.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0059

[Correction method] Change

[Correction contents]

If the arc power value input by the user as a setting condition cannot be realized within the range of the already input current value and a predetermined arc length (for example, 0.7 to 2.0 mm),
(1) An error display may be performed, and the user may re-input the current value or the arc power value. (2) The relation data (for example, FIG. 16 ) between the current and the arc length and the arc power obtained in advance may be displayed. C arranged in the control unit of the pulse welding power supply 1
A predetermined arc length (e.g.,
A current value at which the set arc power can be realized for an intermediate arc length of 1.5 mm may be automatically determined and set.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Kunio Miyazaki 7-1-1, Omika-cho, Hitachi City, Ibaraki Prefecture F-term in Hitachi Research Laboratory, Hitachi, Ltd. F-term (reference) 4E001 AA03 BB06 CC04 DE04 DF08 4E082 AA08 BA04 EA00 EC03 EC13 EF02 EF07 EF15

Claims (6)

[Claims] A welding torch including an arc electrode; a pulse welding power supply for supplying a high-frequency pulse current to the arc electrode; a torch drive unit for adjusting a distance between the arc electrode and a welding base material; An underwater pulse arc welding apparatus including an arc voltage detection unit that detects a voltage between the base metal and the base material, wherein an average value of an arc voltage in a time section from a rising start point to a falling end point of the pulse arc voltage is averaged. An underwater pulse arc welding apparatus characterized in that the torch drive section is operated by adjusting the torch drive section so that the calculated average voltage value matches the arc voltage reference value. 2. A pulse arc welding apparatus according to claim 1, wherein said averaging processing section includes a pulse width detection circuit for a pulse arc voltage, a pulse period measurement circuit, a half-wave rectification circuit, and an arithmetic processing circuit. 3. The pulse arc welding apparatus according to claim 1, wherein the averaging processing section includes a pulse width detection circuit for the pulse arc voltage, an integration circuit for the pulse arc voltage, and an arithmetic processing circuit. 4. The underwater pulse according to claim 1, wherein the averaging processing unit includes a multiplication circuit, an integration circuit, a timing circuit, a pulse width measurement circuit, and an arithmetic processing circuit, and includes a pulse current detection unit. Arc welding equipment. 5. The underwater pulse arc welding apparatus according to claim 1, wherein a voltage waveform shaping processing section is provided before the averaging processing section. 6. An underwater pulse arc welding comprising: a pulse welding power supply for supplying a high-frequency pulse current to an arc electrode; interval adjusting means for adjusting an interval between the arc electrode and a base material; and a pulse arc power calculation unit. In the apparatus, an average value of the arc power in a time section from a rising start point to a falling end point of the pulse arc power is obtained by an averaging processing unit, and the obtained average power value matches the arc power reference value. The underwater pulse arc welding apparatus, wherein the torch drive unit is operated to adjust.